1. Field of the Invention
The present invention relates to a vacuum cleaner, and particularly, to a dust collection unit for a vacuum cleaner, which can reduce airflow noise generated by a cyclone airflow. More particularly, the present invention relates to a dust collection unit for a vacuum cleaner, which can reduce noise generated when air flows with a high speed in a multi-cyclone dust collection unit, thereby attenuating user's unpleasant sensation.
2. Description of the Related Art
A vacuum cleaner is used to clean a room or other spaces by sucking air containing foreign objects and filtering the foreign object using vacuum pressure generated therein. In order to filter the foreign objects contained in the sucked air, a dust collection unit with a filtering unit is provided in the vacuum cleaner.
The filtering unit is classified into a porous filter formed of porous material and a cyclone type filter. The porous filter formed of porous material is designed to filter the foreign objects contained in air while the air passes through the filter. The cyclone type filter is designed to filter the foreign objects using cyclone airflow. In order to reuse the porous filter, a user cleans the filter to remove the foreign objects clogged in the filter. It is very inconvenient to clean the filter. Furthermore, when a large amount of the foreign objects are clogged, the porous filter cannot be reused. Since the cyclone type filter is designed to remove the foreign objects from the air by a rotational air current generated by cyclone airflow, the clogging of the foreign objects in the filter is not incurred. Due to this reason, in recent years, cyclone type filter has been widely used.
In recent years, a multi-cyclone type dust collection unit, in which the cyclone unit is provided in plurality to generate a plurality of cyclone airflows so that the foreign objects contained in the air can be filtered by only the cyclone airflows, has been developed. The multi-cyclone airflows improve the foreign object removal efficiency. In addition, since there is no need to additionally provide the porous filter in the dust collection unit, the clogging problem is not incurred.
However, since the multi-cyclone type dust collection unit is designed to remove the foreign objects using only the cyclone airflows, a plurality of airflow passages should be formed in the collection unit and the passages are in a tangle.
Particularly, when the foreign objects are filtered by a plurality of small cyclone airflows, high frequency noise is generated due to the high speed airflow.